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Name: Elanggovan K.
Status: student
Age: 13
Location: N/A
Country: N/A
Date: 5/13/2003
Question:
What is the difference between boiling and evaporation?

Replies:
Evaporation is a more general term. Evaporation means to change of a liquid into a vapor (gas). It does not matter what the vapor pressure of the substance is. Water at 25 C has a vapor pressure of about 25mm Hg. If a stream of dry air passes over the surface of the water it will evaporate. Eventually there will be no liquid water remaining. On the other hand, "boiling" usually refers to the temperature where the vapor pressure is 1 atmosphere = 760 mm Hg. In the case of water this temperature is 100 C.

Vince Calder

Elanggovan K,

Depending on the conditions that produce them, in both processes molecules in the liquid state are moved into the gaseous state. Evaporation is traditionally looked upon as the slower, relatively quiescent case occurring at or near ambient temperature. Boiling, (a visually more vigorous process) implies some externally applied heat source to speed up the evaporative mechanism. Even so, the fundamental movement of liquid-to-the-vapor-state is essentially the same.

Regards,
ProfHoff 665


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